Study On Rolling And Heat Treatment Of Ti-811 Titanium Alloy Sheet

Ti-811 titanium alloy,with the nominal composition of Ti-8Al-1Mo-1V,is a near ? type heat-resistant titanium alloy with high aluminum content.It has many advantages,such as low density,high modulus of elasticity,good thermal stability,good welding performance and molding performance.It is mainly used in the manufacture of aircraft frame and gas engine parts which require short-range strength,long-range creep resistance,thermal stability and rigidity.Therefore,the development of Ti-811 titanium alloy sheet is of great significance to meet the needs of new aerospace products and the construction of national defense and military industry.In this paper,the rolling parameters of Ti-811 alloy slab are optimized and the rolling process is strictly controlled by using the mature Ti-6Al-4V cladding and stacking rolling process for reference.1.0mm Ti-811 titanium alloy sheet is successfully developed.At the same time,this paper also studied the microstructure evolution of the plate in the rolling process,as well as the influence of different heat treatment systems on the microstructure,room temperature mechanical properties and high temperature mechanical properties of the plate,and discussed the influence of different temperature and stress on the creep properties of the plate.The main results are as follows:By optimizing the rolling parameters such as rolling temperature,deformation and speed,the 1.0mmTi-811 titanium alloy sheet with good surface quality,high dimensional accuracy and good shape can be produced by using the cladding and stacking rolling process,which breaks through the production bottleneck of cold rolling process.The deformation of slab start from single-phase area,and the structure of plate gradually changes from widmanstatten structure to basket structure.Then with the increase of secondary hot rolling deformation,the structure of plate begins to be equiaxed.After the final product is coated and rolled,the structure of plate is composed of equiaxed ?,elongated ? and intergranular ?.After different single annealing,the elongated ? spheroidized and formed equiaxed structure.With the increase of heat treatment temperature,the structure of the plate tends to be uniform,and the grains tend to grow.The room temperature strength and high temperature strength of the plate gradually decrease,and the plasticity increases.The high temperature strength at 400 ? can reach 775 mpa,and the highest high temperature strength at 500 ? can reach 686 MPa.With the increase of stress and temperature,the number of open slip system and plastic deformation ability of the plate increase,which leads to the poor creep performance.Through the microstructure analysis,it is found that the main mechanism of creep is dislocation slip and cross slip.